1. Field of the Invention
The present invention finds principal application within the field of passive solar energy systems. More particularly, the invention relates to a thermosiphon solar energy system which is suitable for preheating water.
2. Prior Art
With the dwindling supplies of fossil fuel and the accompanying increasing energy cost, extensive research efforts are being focused to harness solar radiation on a practical and economical scale. One type of device which shows promise in the field is the passive thermosiphon system, described in U.S. Pat. Nos. 4,137,964 and 4,050,508, issued to Bruce Shawn Buckley. As disclosed in the above references, a "thermic diode" panel collects and stores the sun's radiant energy. The panel typically comprises a shallow, rectangular box that is effectively, divided into two chambers by a slab of insulation. The chambers are filled with a liquid, such as water, and are in open communication with each other at the top and at the bottom of the panel.
Solar radiation, incident on the outer panel face, will heat the water in the collector chamber. As the water is heated, it expands and passes upwardly through the collector chamber and into the cooler storage chamber. Cooler water from the storage chamber, in turn, passes to the bottom of the warmer collector chamber.
Heat may be taken from the storage chamber by means of a simple demand coil heat exchanger as shown in U.S. Pat. No. 4,050,508.
The use of a demand exchanger, however, requires a rather large heat exchange surface area, which, in turn, increases the overall unit cost. Furthermore, the use of water as a heat transport fluid introduces numerous problems, if the unit must perform in freezing temperature extremes.
It is therefore an objective of the present invention to provide an alternative system to the prior art which may be economically manufactured and which will overcome the deficiencies thereof.